U.S. patent application number 13/741820 was filed with the patent office on 2013-05-23 for transmission controlling method, sender apparatus and receiver apparatus for wireless communication system.
This patent application is currently assigned to FUJITSU LIMITED. The applicant listed for this patent is FUJITSU LIMITED. Invention is credited to Hideto FURUKAWA, Kazuo KAWABATA, Yoshihiro KAWASAKI, Kazuhisa OBUCHI, Yoshiaki OHTA, Yoshiharu TAJIMA.
Application Number | 20130129003 13/741820 |
Document ID | / |
Family ID | 39324266 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130129003 |
Kind Code |
A1 |
OHTA; Yoshiaki ; et
al. |
May 23, 2013 |
TRANSMISSION CONTROLLING METHOD, SENDER APPARATUS AND RECEIVER
APPARATUS FOR WIRELESS COMMUNICATION SYSTEM
Abstract
A wireless communication system including a sender apparatus
having a plurality of transmitting antennas that transmits a
plurality of data blocks; and a receiver apparatus that receives
the plurality of data blocks, wherein the sender apparatus
transmits a process number via a control channel different from a
data channel to the receiver apparatus, and wherein the receiver
apparatus performs HARQ processing of received data blocks based on
the received process number which prevents the data blocks from
competing.
Inventors: |
OHTA; Yoshiaki; (Kawasaki,
JP) ; OBUCHI; Kazuhisa; (Kawasaki, JP) ;
KAWABATA; Kazuo; (Kawasaki, JP) ; KAWASAKI;
Yoshihiro; (Kawasaki, JP) ; TAJIMA; Yoshiharu;
(Kawasaki, JP) ; FURUKAWA; Hideto; (Kawasaki,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FUJITSU LIMITED; |
Kanagawa |
|
JP |
|
|
Assignee: |
FUJITSU LIMITED
Kanagawa
JP
|
Family ID: |
39324266 |
Appl. No.: |
13/741820 |
Filed: |
January 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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12424642 |
Apr 16, 2009 |
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13741820 |
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PCT/JP2006/321552 |
Oct 27, 2006 |
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12424642 |
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Current U.S.
Class: |
375/267 |
Current CPC
Class: |
H04L 1/1822 20130101;
H04J 15/00 20130101; H04L 1/1812 20130101; H04L 1/1671 20130101;
H04B 7/0689 20130101; H04L 1/1845 20130101; H04L 1/06 20130101;
H04L 1/1816 20130101 |
Class at
Publication: |
375/267 |
International
Class: |
H04L 1/18 20060101
H04L001/18 |
Claims
1. A wireless communication system comprising: a sender apparatus
having a plurality of transmitting antennas that transmits a
plurality of data blocks; and a receiver apparatus that receives
the plurality of data blocks, wherein the sender apparatus
transmits a process number via a control channel different from a
data channel to the receiver apparatus, and wherein the receiver
apparatus performs HARQ processing of received data blocks based on
the received process number which prevents the data blocks from
competing.
2. A wireless communication method for a wireless communication
system including a sender apparatus having a plurality of
transmitting antennas that transmits a plurality of data blocks;
and a receiver apparatus that receives the plurality of data
blocks, the wireless communication method comprising: on the sender
apparatus, transmitting a process number via a control channel
different from a data channel to the receiver apparatus; and on the
receiver apparatus, performing HARQ processing of received data
blocks based on the received process number which prevents the data
blocks from competing.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation of U.S. application Ser.
No. 12/424,642, filed Apr. 16, 2009, now pending, which is a
continuation of International Application No. PCT/JP2006/321552,
filed on Oct. 27, 2006 in Japan, the entire contents of each are
herein wholly incorporated by reference. The present application
also relates to U.S. application Ser. No. 13/493,529, filed Jun.
11, 2012, now pending and U.S. application Ser. No. 13/493,535,
filed Jun. 11, 2012, now pending.
TECHNICAL FIELD
[0002] The present invention relates to a transmission controlling
method, a sender apparatus and a receiver apparatus for a wireless
communication system, and particularly to a technique suitable for
use with a re-sending controlling technique in MIMO (Multi Input
Multi Output) transmission.
BACKGROUND ART
[0003] While, regarding a mobile communication system such as a
portable telephone system, a service of the third generation method
according to a CDMA (Code Division Multiple Access) method has been
started already, investigations of a next generation mobile
communication system capable of implementing higher-speed
communication on the basis of an OFDMA (Orthogonal Frequency
Division Multiple Access) method are proceeding (refer to
Non-Patent Document 1 hereinafter described).
[0004] Therefore, the MIMO as a technique for increasing the
transmission rate has been proposed as a reliable technique. An
outline of a MIMO transmission system is depicted in FIG. 19. The
MIMO transmission system depicted in FIG. 19 includes a sender
apparatus 100 having a plurality of sending antennas (antenna
systems) Tx#1, Tx#2, . . . , and Tx#n (n is an integer of 2 or
more) and a receiver apparatus 200 having a plurality of receiving
antennas (antenna systems) Rx#1, Rx#2, . . . , and Rx#n, MIMO is a
spatial multiplex transmission technique wherein different data
streams are set in parallel from the sending antennas Tx#i
(i=1.about.n) to increase the transmission capacity in proportion
to the number n of the sending antennas. The different sending
antennas Tx#i are disposed so as not to have correlation with each
other, and the data streams sent from the sending antennas Tx#i
individually pass along fading propagation paths independent of
each other and are received by the receiving antennas Rx#i in a
spatially mixed state with other different data streams.
[0005] As an implementation example of such a MIMO transmission
system as described above, for example, as depicted in FIG. 20, a
method is available wherein a stream process is carried out
independently for each antenna. For example, PARC (Per Antenna Rate
Control) wherein pre-coding (Precoding) is not carried out (refer
to Non-Patent Document 2 hereinafter described), PSRC (Per Stream
Rate Control) wherein pre-coding is carried out (refer to
Non-Patent Document 3 hereinafter described) and so forth are
available.
[0006] In particular, the system depicted in FIG. 20 includes, for
example, the sender apparatus 100 and the receiver apparatus 200.
The sender apparatus 100 includes, for example, a stream separation
section 101, a CRC addition section 102 and a coding section 103 as
well as a HARQ processing section 104 for each sending stream, a
sending section 105 and a re-sending controlling section 106. And
the receiver apparatus 200 includes, for example, a signal
separation and synthesis section 201, a HARQ processing section 202
and a CRC calculation section 203 for each received stream, an
ACK/NACK decision section 204 and a stream synthesis section 205.
It is to be noted that a reference character ATR represents a
receiving antenna of the sender apparatus 100 and another reference
character ATT represents a sending antenna of the receiver
apparatus 200, and, in the present example, it is represented for
the convenience of illustration that an ACK/NACK
(Acknowledgement/Negative Acknowledgement) signal (acknowledgment
signal) is sent from the sending antenna ATT and received by the
receiving antenna ATR.
[0007] Then, the sender apparatus (hereinafter referred to
sometimes as sender side) 100 operates, for example, in accordance
with a flow chart depicted in FIG. 21, and the receiver apparatus
(hereinafter referred to sometimes as receiver side) 200 operates,
for example, in accordance with a flow chart depicted in FIG.
22.
[0008] In particular, in the sender apparatus 100, sending data are
separated into sending streams of the antenna systems Tx#i by the
stream separation section 101 (step A1) and CRC (Cyclic Redundant
Check) codes for error detection are added to each of the sending
streams of the antenna systems Tx#i by the CRC addition section 102
(step A2), and coding of the data streams is carried out for bit
error correction by the coding section 103 and a HARQ (Hybrid
Automatic Repeat request) process is carried out for re-sending
control by the HARQ processing section 104 (step A4). Then, a
sending antenna Tx#i for sending a HARQ block (process) is selected
by the sending section 105, and the HARQ block is modulated and
then sent to the receiver apparatus 200. Here, while, where
pre-coding is used (in case of yes at step A5), each process can
select a plurality of sending antennas Tx#i, in case of the PARC
(in case of no at step A5), each process is sent from a sending
antenna Tx#i determined in advance.
[0009] On the other hand, in the receiver apparatus 200, as
depicted in FIG. 22, if a signal sent from the sender apparatus 100
is received by the receiving antennas Rx#i, then separation and
synthesis of the received signals is carried out by the signal
separation and synthesis section 201 (step B1), and it is decided
whether or not each of the received signals (processes) is a
re-sent process (step B2). As a result, if the received signal is a
re-sent process (in case of yes at step B2), then the receiver
apparatus 200 synthesizes the signal received in the present
reception cycle and a received signal of the same process received
and stored in the preceding reception cycle by means of the HARQ
processing section 202 (step B3), and checks CRC codes added to
each process by means of the CRC calculation section 203 to detect
bit errors (step B4). It is to be noted that, where the process
received in the present reception cycle is not a re-sent process
(in case of no at step B2), synthesis by the HARQ process section
202 is not carried out but bit error detection by the CRC
calculation section 203 is carried out (step B4).
[0010] Then, if a bit error is detected by the ACK/NACK decision
section 204 (in case of yes at step B5), then the received process
is retained and a NACK signal is sent as a reply to the sender
apparatus 100 through the sending antenna ATT (step B6), but, if no
bit error is detected (in case of no at step B5), then an ACK
signal is sent as a reply to the sender apparatus 100 through the
sending antenna ATT and the process is passed to an upper layer
(step B7). It is to be noted that the received signals of the
streams from which no error is detected are synthesized finally by
the stream synthesis section 205 and then outputted.
[0011] In such series of processes as described above, an important
function for high-speed communication is the HARQ. The HARQ is an
ARQ method which is a combination of automatic re-sending request
(ARQ) and error correction coding (FEC: Forward Error Correction).
In particular, on the sender side 100, a block of information bits
is error correction coded with a parity bit for error detection
added, and all or some of the codes. If re-sending occurs, then all
or some of coding bits of the current block are sent.
[0012] On the receiver side 200, the synthesis process is carried
out for individually corresponding bits of an existing block to a
re-sent block, and error correction and error detection process are
carried out again using the synthesis block obtained as a result of
the synthesis process. In this manner, the receiver side 200
repetitively carries out ACK/NACK reply sending to the sender side
100 and trial of a decoding process by re-sending until block
errors are eliminated within a range of a predetermined number of
times as an upper limit.
[0013] In the next generation mobile communication, particularly an
N-channel Stop-and-Wait ARQ is applied (refer to Non-Patent
Document 4 hereinafter described). Here, N represents an integer
and represents the number of blocks (number of processes) which can
be sent at the same time. For each of processes sent at the same
time, re-sending control by the Stop and Wait is carried out.
[0014] An outline of the N-channel Stop-and-Wait ARQ is illustrated
in FIG. 23.
[0015] Each process is sent within a unit interval of wireless
transmission (TTI: Transmission Time Interval) and is identified
with an identifier given as a process number N. In the case of FIG.
23, the process number N is N=5 (0.about.4), and accordingly, the
case of FIG. 23 corresponds to a case of 5-channel Stop-and-Wait
ARQ. It is to be noted that, while it is depicted in FIG. 23 that a
process number is added to the data part of each process for the
convenience of illustration, actually a process number is sent with
a controlling channel and no process number is added to the data
part of each process. In particular, a process number is annexed to
and sent together with the data part of each process (this
similarly applies to the following description).
[0016] If the receiver apparatus 200 receives a process from the
sender apparatus 100, then it carries out error detection in such a
manner as described above. Here, if an error occurs with processes
[1], [3] and [4] but no error occurs with processes [0] and [2],
then regarding the processes [0] and [2] with which no error
occurs, an ACK signal is sent as a reply to the sender apparatus
100, but regarding the processes [1], [3] and [4] with which an
error occurs, a NACK signal is sent as a reply to the sender
apparatus 100 after they are retained into a memory (not depicted).
While also a reply of the ACK/NACK signal is sent with the
controlling channel, in this instance, the process number need not
be sent back.
[0017] The receiver apparatus 200 adjusts the reply sending timing
for each process and sends the ACK/NACK signal as a reply so that
the sender apparatus 100 can identify to which process the ACK/NACK
signal responds. Although, if the sender apparatus 100 receives an
ACK signal, then sending of a new process is carried out, at this
time, a process number which is not used in five processes in the
past may be added arbitrarily including time at which the process
number is added (in FIG. 23, process numbers which are not used are
added in an ascending order).
[0018] On the other hand, although, if the sender apparatus 100
receives a NACK signal, then re-sending of a process with which an
error occurs is carried out, at this time, a process number same as
the process number in the preceding cycle is added. After the
re-sending, the receiver apparatus 200 recognizes the process
number to decide with which process the received process should be
synthesized. In particular, if the processes [1], [3] and [4] which
are re-sent processes are received, then the received processes
[1], [3] and [4] are packet-synthesized with the processes [1], [2]
and [3], respectively, which individually have process numbers same
as those retained upon NACK signal sending in the preceding cycle.
After the synthesis, the CRC codes are checked, and if the
processes are successfully received correctly, then the ACK is sent
as a reply to the sender apparatus 100. On the other hand, if an
error occurs, then the process after the synthesis is retained and
the NACK signal is sent as a reply again to the sender apparatus
100.
[0019] It is to be noted that, while two types of representative
methods are available as a synthesis method, any of the synthesis
methods may be utilized in the present invention. One of the
synthesis methods is a type of a synthesis method wherein data
fully same as that upon former sending is re-sent upon re-sending
and a received signal upon former sending and another received
signal upon re-sending are synthesized with each other to carry out
production of data to be decoded, and the other one of the
synthesis methods is a type of a synthesis method wherein a
puncturing pattern of data after coding is changed upon re-sending
to send bits which are not sent till then and a received signal
upon former sending and another received signal upon re-sending are
synthesized with each other to decrease the equivalent coding ratio
so that the error correction capacity (coding gain) is enhanced.
The latter technique is called IR (Incremental Redundancy).
[0020] Such process processing as described above is carried out in
a similar manner irrespective of difference of the PARC or the
pre-coding. Therefore, description is continuously given below
taking the PARC as an example.
[0021] A manner of the N-channel Stop-and-Wait ARQ where the sender
apparatus 100 and the receiver apparatus 200 are ready for the PARC
is illustrated in FIG. 24.
[0022] Since the CRC addition, coding and HARQ processes are
carried out independently for each antenna in the PARC as described
above, an independent number is added also as a HARQ process
number. In FIG. 24, a manner (refer to arrow marks of broken lines)
is illustrated wherein re-sending occurs with the processes [1],
[3] and [4] sent from the sending antenna Tx#1 and with the process
[1] sent from the sending antenna Tx#2. In such a case as just
described, since the HARQ is carried out for each antenna system as
described above, re-sending control is carried out independently
for each antenna system. It is to be noted that an addition method
of the process number is carried out in accordance with a rule
similar to that in FIG. 23.
[0023] Further, in the MIMO transmission in the next generation
mobile communication system, in order to allow data signals sent
from the different sending antennas Tx#i to be separated and
synthesized among the sending antennas Tx#i, the sender apparatus
100 sends an antenna identification signal (for example, a pilot
signal or a scrambling code).
[0024] An example of pilot signal addition where the two sending
antennas of the sender apparatus 100 are used is depicted in FIG.
25. As depicted in (1) and (2) of FIG. 25, the pilot signal (R:
Reference Symbol) is added in the same time series but in different
frequency series between the antenna systems Tx#1 and Tx#2. The
receiver apparatus 200 refers to the pilot signal to separate a
signal of the antenna system Tx#1 from the received signal by the
antenna system Rx#1 of the receiver apparatus 200 and separates a
signal of the antenna system Tx#2 from the received signal by the
antenna systems Rx#2 of the receiver apparatus 200, and then
synthesizes the separated signals with each other to restore the
sent stream (process). Further, association between the antenna
systems and the pilot signals is sent with notification
information. [0025] Non-Patent Document 1: "3GPP TR25.913 V7.3.0
Requirements for Evolved UTRA (E-UTRA) and Evolved UTRAN (E-UTRAN)
(Release 7)," 3GPP (France), 2006 March [0026] Non-Patent Document
2: Lucent, "Improving MIMO throughput with per-antenna rate control
(PARC)," 3GPP (France), 2001 August [0027] Non-Patent Document 3:
Lucent, "Per Stream Rate Control with Code Reuse TxAA and APP
Decoding for HSDPA," 3GPP (France), 2002 September [0028]
Non-Patent Document 4: "3GPP TR25.814 V7.4.0 Physical Layer Aspects
for evolved Universal Terrestrial Radio Access (UTRA) (Release 7),"
3GPP (France), 2006 June
DISCLOSURE OF THE INVENTION
Subject to be Solved by the Invention
[0029] As a communication environment to which the MIMO
transmission system is applied, for example, such a cell
configuration as depicted in FIG. 26 is available. In particular,
the cell configuration depicted in FIG. 26 is a form wherein one
cell is divided into areas depending upon the form of the MIMO
transmission, and where a mobile station 400 exists in an area
(MIMO multiplex transmission area) 302 on the inside of the base
station 300 as depicted in (1) of FIG. 26, the MIMO multiplex
transmission (in (1) of FIG. 26, sent with 2 streams) is used.
However, where the mobile station 300 exists in an area (non-MIMO
multiplex transmission area) 303 on the outside of the base station
300, non-MIMO multiplex transmission (in (1) of FIG. 26, 1-stream
transmission) is used. It is to be noted that the "non-MIMO
multiplex transmission" signifies MIMO diversity transmission or
MIMO single transmission wherein sending and reception of one
stream are carried out with one antenna.
[0030] Further, as depicted in (2) of FIG. 26, where, even in the
MIMO multiplex transmission area 302, the mobile station 400 is
within an area 301 in the proximity of the base station 300 and
line-of-sight communication is available, also there is a case
wherein non-MIMO multiplex transmission (1-stream transmission in
(2) of FIG. 26) is carried out on purpose. This is because, in the
case of the line-of-sight communication, since an inter-antenna
correlation occurs, there is the possibility that separation and
synthesis of signals by the receiver apparatus 200 may be difficult
and a high throughput cannot be obtained.
[0031] In such a case as just described, there is the possibility
that, even if the mobile station 400 is in the area 301 in the
proximity of the base station 300, a higher throughput may be
obtained if not the MIMO multiplex transmission but non-MIMO
multiplex transmission is carried out with a high degree of
modulation and a high coding ratio.
[0032] In this manner, the MIMO multiplex transmission is applied
not fixedly in 1 cell, but non-MIMO multiplex transmission is
sometimes applied depending upon the existing position of the
mobile station 400. For example, the MIMO multiplex transmission is
carried out where the wireless quality (for example, an average
value of the SN ratio with which the mobile station 400 reports to
the base station 300) of the mobile station 400 is higher than a
certain threshold value, but non-MIMO multiplex transmission is
carried out where the wireless quality is lower than the threshold
value.
[0033] At this time, since the number of streams decreases from
plural streams to one stream, in the method wherein a process
number is added independently for each antenna system, for example,
like the PARC, when the number of streams decreases, the
possibility occurs that communication cannot be continued because
process numbers of the HARQ overlap (compete) with each other.
[0034] For example, an example of operation where the transmission
mode is changed over from the MIMO multiplex transmission to the
MIMO diversity transmission in the PARC is illustrated in FIG. 27.
The example indicates a case wherein the ACK/NACK signal is sent as
a reply with one stream.
[0035] It is assumed that processes [0], [1] and [2] are sent from
the antenna systems Tx#1 and Tx#2 of the sender apparatus 100 at
such timings as illustrated in FIG. 27 and, after the ACK signals
corresponding to the processes [0] and [1] sent from the antenna
systems Tx#1 and Tx#2 are sent as replies from the receiver
apparatus 200 to the sender apparatus 100, the existing position of
the mobile station 400 is moved at a timing indicated by reference
numeral 500 in FIG. 27 from the MIMO multiplex transmission area
302 to the non-MIMO multiplex transmission (MIMO diversity
transmission area) area 301 or 303 which are depicted in FIG.
26.
[0036] At this time, if the main antenna system of the sender
apparatus 100 for carrying out a process of a stream flowing
therein is the antenna system Tx#2, then the sender apparatus 100
sends the process [2] accumulated before the transmission mode is
changed over to the MIMO diversity transmission from the antenna
systems Tx#1 and Tx#2. The receiver apparatus 200 receives the
signals by means of the antenna systems Rx#1 and Rx#2 and carries
out synthesis of the received signals to construct the process [2].
Then, although the receiver apparatus 200 tries to carry out packet
synthesis between the constructed process [2] and the process [2]
retained upon sending in the last cycle, the following subject
arises here.
[0037] (Subject 1) The receiver apparatus 200 cannot recognize with
which retained process the re-sent process [2] should be
synthesized. In particular, for example, while the receiver
apparatus 200 receives the re-sent process [2] with the MIMO
diversity as depicted in FIG. 28, where the packet synthesis is
carried out referring only to the process number as described
above, since the process [2] is retained by both of the antenna
system. Rx#1 and the antenna system Rx#2, it cannot be decided with
which process the synthesis should be carried out. For example, if
the synthesis with the process (refer to reference numeral 601)
retained by the main antenna system Rx#2 is attempted, then the
packet synthesis between the process [2] (refer to reference
numeral 602) of the antenna system Rx#1 and the process [2] of the
antenna system Rx#2 indicated by reference numeral 601 is carried
out, resulting in deterioration of the matching property of the
synthesis.
[0038] In addition, also the following subject arises.
[0039] (Subject 2) In the sender apparatus 100, such re-sending in
error as described in cases 1 and 2 below occurs.
[0040] (Case 1) where Sending of the ACK/NACK Signal as a Reply is
Carried Out Through Timing Adjustment
[0041] In this instance, the reply timing (reply sending time and
reply frequency) of the ACK/NACK signal is conveyed to the mobile
station by the base station.
[0042] An outline is illustrated in FIG. 29. The receiver apparatus
200 sends the ACK/NACK signal as a reply through the timing
adjustment of the main antenna system Rx#2. At this time, the
sender apparatus 100 receives the reply with timing information of
the main antenna system Tx#2. In this case, since the timing at
which the sender apparatus 100 receives the replay overlaps with
the re-sending timing of the process [2] of the antenna systems
Tx#2 denoted by reference numeral 603 as seen in FIG. 29, there is
the possibility that, while the process [2] of the antenna systems
Tx#1 is to be re-sent originally, the process [2] of the antenna
systems Tx#2 may possibly be re-sent in error. At this time, the
process [2] of the antenna system Tx#1 cannot be re-sent.
[0043] (Case 2) Where Sending of a Reply of the ACK/NACK Signal is
Carried Out not Through Time Timing Adjustment but Through the
Process Number
[0044] The case 2 is a case wherein sending of a reply of the
ACK/NACK signal is executed without carrying out the timing
adjustment. Accordingly, different from the case 1, while the
instruction of the reply timing adjustment need not be carried out,
the process number must be applied upon reply of the ACK/NACK.
[0045] An outline is illustrated in FIG. 30. The receiver apparatus
200 sends a reply of the ACK/NACK signal explicitly indicating the
process number from the main antenna systems Rx#2. Thereupon, the
reply is received by the antenna systems Tx#2. At this time, if the
reply for the process [2] of the antenna system Tx#1 is received,
then the sender apparatus 100 misinterprets the reply as a NACK
signal with regard to the process [2] of the antenna system Tx#2 as
seen in FIG. 30. Therefore, the process [2] of the antenna system
Tx#1 cannot be re-sent.
[0046] In this manner, a subject gives rise that, if overlapping of
a process number occurs between different antenna systems, then the
receiver apparatus 200 cannot decide which processes of which
antenna systems should be synthesized with each other while, in the
sender apparatus 100, re-sending in error of a process occurs and
the process to be re-sent originally cannot be re-sent.
[0047] Further, also where an acknowledgment (ACK/NACK signal) is
sent as a replay from the receiver apparatus 200 to the sender
apparatus 100 with 2 streams, a subject similar to that described
above arises. A manner of this is illustrated in FIGS. 31 and 32.
In particular, in the receiver apparatus 200, it cannot be decided
with which one of the processes retained by the antenna system Rx#1
and the antenna system Rx#2 the re-sent process [2] should be
synthesized as seen in FIG. 28. Further, also in the sender
apparatus 100, subjects similar to those described with reference
to FIGS. 29 and 30 occur.
[0048] In particular, if the transmission mode is changed over from
the MIMO multiplex transmission to the MIMO diversity transmission,
then:
[0049] (1) while, where an acknowledgment to be sent as a replay
from the receiver apparatus 200 is sent as a reply from the antenna
system Rx#2, the ACK/NACK signal is sent back from the sending
antenna ATT 2 of the receiver apparatus 200 as seen in FIG. 31,
since, in this instance, the operation of the sender apparatus 100
is similar to those in the cases illustrated in FIGS. 29 and 30,
the process [2] of the antenna system Tx#2 is re-sent in error and
the process [2] of the antenna system Tx#1 cannot be re-sent;
[0050] (2) while, where an acknowledgment to be sent as a replay
from the receiver apparatus 200 is sent as a reply by the MIMO
diversity, since the ACK/NACK signal is sent through the sending
antennas ATT1 and ATT2 as seen in FIG. 32, the sender apparatus 100
carries out diversity reception of the signals sent as a reply from
the receiving antennas ATR1 and ATR2. However, since the main
antenna systems is the antenna system Tx#2, it is decided finally
that the signals described above are replies for the antenna system
Tx#2. Therefore, the process [2] of the antenna system Tx#2 is
re-sent in error and the process [2] of the antenna system Tx#1
cannot be re-sent.
[0051] The present invention has been made in view of such subjects
as described above, and it is an object of the present invention to
maintain the matching property of process numbers (that is, stream
identification) so that communication can be continued normally
also where the number of transmission streams varies (decreases) as
in a case wherein the transmission mode is changed over from the
MIMO multiplex transmission to the MIMO diversity transmission.
Means for Solving the Subjects
[0052] In order to attain the object described above, the present
invention is characterized in that a transmission controlling
method, a sender apparatus and a receiver apparatus for a wireless
communication system are used. Particularly:
[0053] (1) According to the present invention, there is provided a
first mode of a transmission controlling method for a wireless
communication system wherein a plurality of stream data can be
transmitted in a unit of a predetermined data block from a sender
apparatus having a plurality of sending antennas to a receiver
apparatus, wherein the sender apparatus annexes, for each of the
plural stream data, data block identification information which is
not competitive between the stream data to the data block and sends
the resulting data block to the receiver apparatus, and the
receiver apparatus carries out, based on the data block
identification information annexed to the received data block from
the sender apparatus, a re-sending synthesis process for the data
block received already and a re-sent data block to both of which
the same data block identification information is annexed.
[0054] (2) Here, information including an antenna identifier
relating to any of the sending antennas which sends the stream data
may be annexed as the data block identification information to the
data block.
[0055] (3) Also, information of a series of numbers may be divided
into groups for each of the stream data and the number information
in a corresponding group may be annexed as the data block
identification information to the data block for each of the stream
data.
[0056] (4) Further, the receiver apparatus may add the data block
identification information to a re-sending request for the received
data block and send the resulting re-sending request to the sender
apparatus, and the sender apparatus may receive the re-sending
request and re-send the data block identified based on the data
block identification information added to the re-sending request as
the re-sent data block to the receiver apparatus.
[0057] (5) Further, according to the present invention, there is
provided a second mode of a transmission controlling method for a
wireless communication method wherein a plurality of stream data
can be transmitted from a sender apparatus having a plurality of
sending antennas to a receiver apparatus, wherein the sender
apparatus detects a decrease control factor of the number of the
stream data, and delays, if the decrease control factor is
detected, a decrease control timing of the number of the stream
data in response to an amount of unsent data regarding stream data
which is a decrease control target.
[0058] (6) Here, the sender apparatus may carry out the decrease
control after sending of the unsent data is completed.
[0059] (7) Also, the sender apparatus may monitor wireless quality
with the receiver apparatus, and carry out, if the wireless quality
becomes lower than a predetermined threshold value, the decrease
control even if sending of the remaining data is not completed.
[0060] (8) Further, the sender apparatus may monitor wireless
quality with the receiver apparatus, and carry out, if there is no
remaining data of stream data which is a decrease target at a point
of time at which the wireless quality becomes lower than a
predetermined threshold value, the decrease control of the number
of the streams at the point of time.
[0061] (9) Further, according to the present invention, there is
provided a sender apparatus for a wireless communication system
wherein a plurality of stream data can be transmitted in a unit of
a predetermined data block from the sender apparatus which has a
plurality of sending antennas to a receiver apparatus, comprising a
data block identification information annexing section adapted to
annex, for each of the plural pieces of the stream data, data block
identification information to the data block, a sending section
adapted to send the data block to which the data block
identification information is annexed to the receiver apparatus,
and a controlling section adapted to control the data block
identification information annexing section such that the data
block identification information to be annexed to the data block is
not competitive between the stream data.
[0062] (10) Here, the controlling section may comprise an antenna
identifier production section for providing information including
an antenna identifier relating to any of the sending antennas for
the data streams as the data block identification information to be
annexed to the data block of the data stream to the data block
identification information annexing section.
[0063] (11) Also, the controlling section may comprise a
group-based number production section for dividing information of a
series of numbers into groups for each data stream and providing,
for each data stream, the number information in a corresponding
group as the data block identification information to be annexed to
the data block to the data block identification information
annexing section.
[0064] (12) Further, the transmission apparatus for a wireless
communication system may further comprise a re-sending controlling
section adapted to re-send, where a re-sending request for the
received data block to which the data block identification
information is annexed is received from the receiver apparatus, the
data block identified with the data block identification
information to the receiver apparatus.
[0065] (13) Further, according to the present invention, there is
provided a receiver apparatus for a wireless communication system
wherein a plurality of stream data can be transmitted in a unit of
a predetermined data block from a sender apparatus having a
plurality of sending antennas to the receiver apparatus, wherein a
reception section adapted to receive a data block to which data
block identification information which is not competitive between
the stream data is annexed for each of the plural stream data by
the sender apparatus and which is sent from the sender apparatus,
and a re-sending synthesis section adapted to carry out, based on
the data block identification information annexed to the received
data block received by the reception section, a re-sending
synthesis process for the data block received already and a re-sent
data block to both of which the same data block identification
information is annexed.
[0066] (14) Further, the receiver apparatus for a wireless
communication system may further comprise a re-sending request
sending section adapted to annex the data block identification
information to a re-sending request for the received data block and
send the resulting re-sending request to the sender apparatus.
Effect of the Invention
[0067] With the present invention, at least such an effect and an
advantage as described just below are obtained.
[0068] In particular, also in a case wherein the number of
transmission streams between the sender apparatus and the receiver
apparatus varies (decreases) as in a case wherein the transmission
mode is changed over from the MIMO multiplex transmission to
non-MIMO multiplex transmission (MIMO diversity transmission or the
like), since competition of data block identification does not
occur between the transmission streams, re-sending in error of a
data block from the sender apparatus and synthesis in error of the
data block in the receiver apparatus can be avoided. Accordingly,
normal communication (stream transmission) can be continued between
the sender apparatus and the receiver apparatus.
BRIEF DESCRIPTION OF THE DRAWINGS
[0069] FIG. 1 is a block diagram depicting a configuration of a
MIMO transmission system according to a first embodiment of the
present invention.
[0070] FIG. 2 is a block diagram illustrating a process number
addition method for the MIMO transmission system depicted in FIG. 1
and depicting an example of a process number together.
[0071] FIG. 3 is a view illustrating re-sending process operation
in the MIMO transmission system depicted in FIG. 1.
[0072] FIG. 4 is a flow chart illustrating operation of a sender
apparatus in the MIMO transmission system depicted in FIG. 1.
[0073] FIG. 5 is a view illustrating a reply sending method (case
1) of an ACK/NACK in the MIMO transmission system depicted in FIG.
1.
[0074] FIG. 6 is a flow chart illustrating operation (case 1) of a
receiver apparatus in the MIMO transmission system depicted in FIG.
1.
[0075] FIG. 7 is a view illustrating a reply sending method (case
2) of an ACK/NACK in the MIMO transmission system depicted in FIG.
1.
[0076] FIG. 8 is a flow chart illustrating operation (case 2) of
the receiver apparatus in the MIMO transmission system depicted in
FIG. 1.
[0077] FIG. 9 is a block diagram depicting a configuration of a
MIMO transmission system according to a second embodiment of the
present invention together with an example of a process number.
[0078] FIG. 10 is a block diagram illustrating a different process
number addition method for the MIMO transmission system depicted in
FIG. 9 and depicting an example of a process number together.
[0079] FIG. 11 is a view illustrating re-sending process operation
in the MIMO transmission system depicted in FIG. 9.
[0080] FIG. 12 is a flow chart illustrating operation of a sender
apparatus in the MIMO transmission system depicted in FIG. 9.
[0081] FIG. 13 is a flow chart illustrating operation (case 1) of a
receiver apparatus in the MIMO transmission system depicted in FIG.
9.
[0082] FIG. 14 is a flow chart illustrating operation (case 2) of
the receiver apparatus in the MIMO transmission system depicted in
FIG. 9.
[0083] FIG. 15 is a view illustrating re-sending process operation
in a MIMO transmission system according to a third embodiment of
the present invention.
[0084] FIG. 16 is a view illustrating a MIMO transmission
changeover method according to the third embodiment.
[0085] FIG. 17 is a view illustrating a MIMO transmission
changeover method according to a fourth embodiment of the present
invention.
[0086] FIG. 18 is a view illustrating re-sending process operation
in a MIMO transmission system according to the fourth
embodiment.
[0087] FIG. 19 is a schematic view of a MIMO transmission
system.
[0088] FIG. 20 is a block diagram depicting an example of a
configuration of a sender apparatus and a receiver apparatus in the
MIMO transmission system depicted in FIG. 19.
[0089] FIG. 21 is a flow chart illustrating operation of the sender
apparatus in the MIMO transmission system depicted in FIG. 20.
[0090] FIG. 22 is a flow chart illustrating operation of the
receiver apparatus in the MIMO transmission system depicted in FIG.
20.
[0091] FIG. 23 is a view illustrating a re-sending synthesis
process in the MIMO transmission system depicted in FIG. 20.
[0092] FIG. 24 is a view illustrating a manner of N-channel
Stop-and-Wait ARQ where the sender apparatus and receiver apparatus
in the MIMO transmission system depicted in FIG. 20 are ready for
the PARC.
[0093] FIG. 25 is a view illustrating an example of pilot signal
addition in the MIMO transmission system depicted in FIG. 20.
[0094] FIG. 26 is a block diagram depicting an example of a cell
configuration of the MIMO transmission system.
[0095] FIG. 27 is a view illustrating an example of operation where
the transmission mode is changed over from MIMO multiplex
transmission to MIMO diversity transmission in the PARC.
[0096] FIG. 28 is a view illustrating a subject of the prior
art.
[0097] FIG. 29 is a view illustrating another subject of the prior
art.
[0098] FIG. 30 is a view illustrating a further subject of the
prior art.
[0099] FIG. 31 is a view illustrating a still further subject of
the prior art.
[0100] FIG. 32 is a view illustrating a yet further subject of the
prior art.
DESCRIPTION OF REFERENCE CHARACTERS
[0101] 1 sender apparatus (base station) [0102] 11 stream
separation section [0103] 12 CRC addition section [0104] 13 coding
section [0105] 14 HARQ sending processing section (data block
identification information addition means) [0106] 15 sending
section [0107] 16 re-sending controlling section [0108] 17, 17A
process number addition section (controlling means: antenna
identifier production section, group-based number production
section) [0109] 2 receiver apparatus (mobile station) [0110] 21
signal separation and synthesis section (reception means) [0111] 22
HARQ reception processing section (re-sending synthesis means)
[0112] 23 CRC calculation section [0113] 24 ACK/NACK decision
section (re-sending request sending means) [0114] 25 stream
synthesis section 25 [0115] 26, 26A process number distribution
section
[0116] Tx#1, Tx#2, . . . , Tx#n sending antenna (antenna system)
[0117] Rx#1, Rx#2, . . . , Rx#n receiving antenna (antenna system)
[0118] ATT sending antenna [0119] ATR receiving antenna
BEST MODE FOR CARRYING OUT THE INVENTION
[0120] In the following, embodiments of the present invention are
described with reference to the drawings. It is to be noted,
however, that it is a matter of course that the present invention
is not limited to the embodiments described below but can be
carried out in various modified forms without departing from the
scope of the present invention.
[A] Description of the First Embodiment
[0121] FIG. 1 is a block diagram depicting a configuration of a
MIMO transmission system according to a first embodiment of the
present invention, and the MIMO transmission system depicted in
FIG. 1 includes at least one sender apparatus 1 having a plurality
of sending antennas (antenna systems) Tx#1, Tx#2, . . . and Tx#n
and at least one receiver apparatus 2 having a plurality of
receiving antennas (antenna systems) Rx#1, Rx#2, . . . and Rx#n. It
is to be noted that the sender apparatus 1 can be applied, for
example, as a sending system of a base station apparatus and the
receiver apparatus 2 can be applied as a receiving system of a
mobile station apparatus. Further, while the number of sending
antennas and the number of receiving antennas are equal to each
other (n) in the present embodiment, the numbers may be different
from each other.
[0122] Then, taking notice of essential part of the sender
apparatus 1, the sender apparatus 1 includes, for example, a stream
separation section 11, a CRC addition section 12 and a coding
section 13 as well as a HARQ sending processing section 14 for each
sending stream, a sending section 15, a re-sending controlling
section 16 and a process number addition section 17. Meanwhile,
taking notice of essential part of the receiver apparatus 2, the
receiver apparatus 2 includes, for example, a signal separation and
synthesis section 21, a HARQ reception processing section 22 and a
CRC calculation section 23 for each received stream, an ACK/NACK
decision section 24, a stream synthesis section 25 and a process
number distribution section 26. It is to be noted that, also in
FIG. 1, reference character ATR represents a receiving antenna of
the sender apparatus 1 and ATT represents a sending antenna of the
receiver apparatus 2, and it is premised for the convenience of
description that an acknowledgment (ACK/NACK signal) is sent from
the sending antenna ATT of the receiver apparatus 2 with one stream
and then is received by the receiving antenna ATR of the sender
apparatus 1.
[0123] Here, in the sender apparatus 1, the stream separation
section 11 separates a sending data signal into sending streams of
the antenna systems Tx#i and the CRC addition sections 12 add CRC
codes for error detection to the sending streams, and the coding
sections 13 carry out coding of the sending streams to which the
CRC codes are added into required error correction codes such as
turbo codes or the like.
[0124] The HARQ sending processing sections 14 carry out a HARQ
process (blocking) for the sending streams for each process number
and then transfer the resulting sending streams to the sending
section 15, and temporarily retain the HARQ blocks (processed) into
a memory not depicted in preparation for re-sending control. The
sending section 15 carries out a required wireless sending process
including modulation by a required modulation method (for example,
QPSK, 16QAM, 64QAM or the like), DA conversion, frequency
conversion (up convert) into wireless frequency (RF) signals and so
forth for the processes inputted from the HARQ sending processing
sections 14 and sends the resulting process to the receiver
apparatus 2 through one of the sending antennas Tx#i.
[0125] The re-sending controlling section 16 decides whether or not
re-sending is required based on the ACK/NACK signal from the
receiver apparatus 2 received through the receiving antenna ATR and
specified, if it is decided that re-sending is required, an antenna
system Tx#i to be used for re-sending and a process to be re-sent.
Then, the re-sending controlling section 16 controls so that, from
the memory of the HARQ sending processing section 14 corresponding
to the antenna systems Tx#i of the re-sending target, the retained
process is read out and then the read out process is transferred to
the sending section 15. It is to be noted that the antenna systems
Tx#i to be used for re-sending and the process to be re-sent can be
specified, for example, through timing adjustment of the previously
described ACK/NACK signal or explicit indication of the process
number for the ACK/NACK signal hereinafter described.
[0126] Then, the process number addition section 17 adds a process
number for each HARQ block (data block) in each HARQ sending
processing section 14, and, in the present embodiment, information
having a format of (antenna identifier)+(number) is applied as the
process number to the HARQ sending processing section 14 so that
information which is not competitive (does not overlap) among the
antenna systems Tx#i (sending streams), that is, a sending stream
identifier, is added to the sending stream. For example, as
depicted generally in FIG. 2, the process number to be added to the
sending stream of the antenna system Tx#1, process number to be
added to the sending stream of the antenna system Tx#2 and process
number to be added to the sending stream of the antenna system Tx#n
can be represented as "0 . . . 00xxx", "0 . . . 01yyy" and "1 . . .
11zzz" in bit string representation (where x, y and z individually
represent 0 or 1), respectively. The sender apparatus 1 adds such
unique process numbers as just described to the sending streams and
transmits the resulting sending streams to the receiver apparatus
2.
[0127] In particular, each HARQ sending processing section 14
implements a function as a data block identification information
addition section for adding a process number (data block
identification information) to a process (data block) for each of
plural streams and the process number addition section 17
implements a function as a controlling section for controlling the
HARQ sending processing section 14 so that the process numbers
added to the processes are not competitive among the streams.
Further, the process number addition section 17 implements also a
function as an antenna identifier production section for applying
information including an antenna identifier regarding a sending
antenna Tx#i of a stream as the process number to be added to the
process of the stream to the HARQ sending processing section
14.
[0128] On the other hand, in the receiver apparatus 2, the signal
separation and synthesis section 21 can separate, under the control
of the process distribution section 26, a signal sent from the
sending antennas Tx#i (i=1 to n) and received in a spatially
multiplexed state by the receiving antennas Rx#i for each process
and carry out, upon MIMO diversity, a diversity synthesis process.
Then, the HARQ reception processing sections 22 store the received
streams (processes) obtained by the signal separation and synthesis
section 21 together with the process number in preparation for the
re-sending synthesis process and synthesize the stored processes
with re-sent processes having the same process number from the
sender apparatus 1.
[0129] In particular, the signal separation and synthesis section
21 implements a function as a reception section for receiving a
process sent after with a process number (number information
including an antenna identifier), which is not competitive among
the streams, added for each stream by the sender apparatus 1, and
each HARQ reception processing section 22 implements a function as
a re-sending synthesis section for carrying out a re-sending
synthesis process between a process received already and a re-sent
process to which the same process is added based on the process
number added to the received process received by the signal
separation and synthesis section 21 as the reception section.
[0130] Each CRC calculation section 23 carries out CRC calculation
for a received stream obtained by the HARQ reception processing
section 22 to carry out error check, and the ACK/NACK decision
section 24 produces an acknowledgment signal based on a result of
the CRC calculation and sends (feeds back) the produced signal from
the sending antenna ATT to the sender apparatus 1. In particular,
the ACK/NACK decision section 24 produces an ACK signal where the
CRC calculation result indicates a normal state (OK) but produces a
NACK signal where the CRC calculation result indicates an abnormal
state (NG), and feeds back the produced signal to the sender
apparatus 1.
[0131] It is to be noted, however, that, as hereinafter described,
the ACK/NACK decision section 24 in the present embodiment can add
part (antenna identifier) or all (process number) of the process
number information to the acknowledgment signal (ACK/NACK signal)
and sends the resulting signal to the sender apparatus 1. In other
words, the ACK/NACK decision section 24 in the present embodiment
implements a function as a re-sending request sending section for
adding an antenna identifier or a process number to a re-sending
request (NACK signal) regarding a receiving process and sending the
resulting signal to the sender apparatus 1.
[0132] The stream synthesis section 25 synthesizes those streams
whose CRC calculation result by the CRC calculation sections 23
indicate OK with each other and outputs a result of the synthesis
as received data.
[0133] Then, the process distribution section 26 identifies the
process number of the received process and controls the signal
separation and synthesis process by the signal separation and
synthesis section 21 so that the received process is distributed
and inputted to one of the HARQ reception processing sections 22.
It is to be noted that, in order to allow identification of the
process number, in the process distribution section 26, information
relating to the process number to be used in the process number
addition section 17 and an addition method of the process number is
stored in advance in a memory or the like not depicted, and the
addition method of the process number is shared between the sender
apparatus 1 and the receiver apparatus 2.
[0134] Operation of the MIMO transmission system of the present
embodiment configured in such a manner as described above is
described below with reference to FIGS. 3 to 8.
[0135] First, in the sender apparatus 1, the stream separation
section 11 separates sending data into sending streams for the
antenna systems Tx#i and the corresponding CRC addition sections 12
add CRC codes individually to the sending streams. Thereafter, the
coding sections 13 perform coding into required error correction
codes such as turbo codes or the like for the individual sending
streams and input the resulting sending streams to the HARQ sending
processing sections 14.
[0136] Each of the HARQ sending processing sections 14 performs a
HARQ process (blocking) for the corresponding sending stream
inputted from the corresponding coding section 13 and adds a
process number to the corresponding sending stream under the
control of the process number addition section 17 as seen in FIG.
2, and then retains a HARQ block (process) in preparation for the
re-sending control and transfers the HARQ block to the sending
section 15.
[0137] Consequently, the sending section 15 carries out the above
described wireless sending process for the processes inputted from
the HARQ sending processing sections 14 and sends a resulting
process to the receiver apparatus 2 through one of the sending
antennas Tx#i. A concept of a manner of this is illustrated in FIG.
3. FIG. 3 illustrates the manner in a case wherein the sending and
receiving antenna systems individually indicate n=2, and a manner
is illustrated in FIG. 3 that it is determined that the "antenna
identifiers" of the antenna systems Tx#1 and Tx#2 are "0" and "1",
respectively, and the "number" of the HARQ blocks is 0, 1, 2 and .
. . , and process numbers such as "0-0", "0-1", "0-2" or . . . are
successively added individually to the processes to be sent from
the antenna systems Tx#1 and process numbers such as "1-0", "1-1",
"1-2" or . . . are successively added individually to the processes
to be sent from the antenna systems Tx#2. Then, the resulting
processes are sent to the receiver apparatus 2 (refer to solid line
arrow marks directed toward the downward direction on the plane of
FIG. 3).
[0138] It is to be noted that the sender apparatus 1 carries out
the stream sending while maintaining the addition method of the
process number by the process number addition section 17 similarly
as in the case described above also after the number of used
antenna systems decreases as in the case wherein a changeover from
the MIMO multiplex transmission to the MIMO diversity transmission
(hereinafter referred to sometimes as transmission mode changeover)
occurs (refer to reference numeral 500 in FIG. 3). Here, if the
stream sending by the antenna systems other than the main antenna
system Tx#i ends, then the sending and receiving of a process may
be carried out with the antenna identifier omitted. However, the
"main antenna system" signifies an antenna system used even before
and after the transmission mode changeover (this similarly applies
to the following description) and is the antenna system Tx#2 in the
example of FIG. 3.
[0139] An operation flow chart of the sender apparatus 1 including
such an option as described above is depicted in FIG. 4. In
particular, the sender apparatus 1 carries out sending of a stream
with a process number annexed as described above by means of the
process number addition section 17 (step S11) and monitors and
decides whether or not a transmission mode changeover (change to
the MIMO diversity transmission) occurs by means of the re-sending
controlling section 16 (step S12). If the transmission mode
changeover does not yet occur (in case of no at step S12), then the
re-sending controlling section 16 controls the process number
addition section 17 and the HARQ sending processing section 14 so
that the sending of a stream to which a process number is added is
continuously carried out as it is.
[0140] On the other hand, if a transmission mode changeover occurs
(in case of yes at step S12), then the re-sending controlling
section 16 decides whether or not data (process) to be sent from
any of the antenna systems other than the main antenna system Tx#i
is absent (step S13), and, if such data is present (in case of no
at step S13), then the re-sending controlling section 16 controls
the process number addition section 17 and the HARQ sending
processing section 14 so that a process number is added by the
process number addition section 17 and then stream sending is
carried similarly as at step S11 (step S14).
[0141] On the other hand, if data (process) to be sent from any of
the antenna systems other than the main antenna systems Tx#i is
absent (in case of yes at step S13), then the re-sending
controlling section 16 controls the process number addition section
17 and the HARQ sending processing section 14 so that a process
number from which the antenna identifier which is an element of the
process number is omitted is added and then carries out stream
sending (step S15).
[0142] On the other hand, in the receiver apparatus 2, a signal
received by each of the receiving antennas Rx#i is separated into
different processes by the signal separation and synthesis section
21 and each separated signal is distributed to one of the HARQ
reception processing sections 22 under the control of the process
distribution section 26.
[0143] The HARQ reception processing section 22 stores the receive
process from the signal separation and synthesis section 21
together with the process number in preparation for the re-sending
synthesis process and synthesizes a re-sent process having the same
process number and re-sent from the sender apparatus 1 with the
stored process (where there is no re-sent process, the received
process is outputted as it is).
[0144] Thereafter, CRC calculation is carried out for the received
process outputted from the HARQ reception processing section 22 by
the corresponding CRC calculation section 23 and an acknowledgment
signal (ACK signal or NACK signal) according to a result of the
calculation is produced by the ACK/NACK decision section 24. Then,
the produced signal is fed back to the sender apparatus 1 through
the sending antenna ATT (refer to arrow marks directed upwardly on
the plane of FIG. 3). However, the ACK/NACK decision section 24
applies the antenna identifier or the process number to the
acknowledgment signal.
[0145] It is to be noted that any process with regard to which the
CRC calculation result is normal is synthesized with processes of
different received streams by the stream synthesis section 25 and a
result of the synthesis is outputted as data which is successfully
received correctly, but any process with regard to which the CRC
calculation result is abnormal is abandoned without being inputted
to the stream synthesis section 25.
[0146] Further, the sender apparatus 1 controls the process number
addition section 17 and the HARQ sending processing section 14 in
order to send a new process if the ACK signal is received as the
acknowledgment signal from the receiver apparatus 2 but to re-send
the process with regard to which the decision result in the
receiver apparatus 2 is abnormal if the NACK signal is received. It
is to be noted that the process to be newly sent or re-sent is
specified based on the antenna identifier or the process number
included in the received acknowledgment signal.
[0147] Consequently, the HARQ sending processing section 14 can
re-send, also upon process re-sending, a process having the process
number same as that upon sending in the preceding cycle and the
receiver apparatus 2 can carryout correct synthesis of the process
by means of the HARQ reception processing section 22 even if the
number of sending streams (number of sending antennas) is
fluctuated as in a case wherein the transmission mode is changed
over from the MIMO multiplex transmission to non-MIMO multiplex
transmission such as the MIMO diversity transmission, MIMO single
transmission or the like through the identification of the received
process number and the distribution control of the received process
by the process distribution section 26.
[0148] For example, if a case wherein the changeover to the MIMO
diversity transmission occurs at a timing indicated by reference
numeral 500 in FIG. 3 to reduce the number of the sending antennas
from two to one (only the antenna systems Tx#2) is considered, then
whichever process number a re-sent process received from the sender
apparatus 2 after the changeover just described (refer to a double
arrow mark directed downwardly on the plane of FIG. 3) has, the
receiver apparatus 2 can carry out correct distribution of the
process by means of the process distribution section 26 so that the
correct synthesis of processes, that is, synthesis of the processes
individually having the process numbers same as each other, is
carried out. In particular, degradation of the matching property of
the synthesis can be prevented (the subject 1 described above can
be solved).
[0149] Further, by contriving the replying method of the ACK/NACK
in such a manner as given in cases 1 and 2 described below, also
the subject 2, that is, the subject that, in the sender apparatus
1, re-sending in error of a process occurs and a process to be
originally re-sent cannot be re-sent, can be solved.
[0150] (Case 1) Where the ACK/NACK Signal is Received Through
Timing Adjustment (FIGS. 5 and 6)
[0151] A diagram of a concept in the present case corresponding to
FIG. 3 is depicted in FIG. 5. As depicted in FIG. 5, also after a
transmission mode changeover (change to the MIMO diversity
transmission) occurs (refer to reference numeral 500), the receiver
apparatus 2 utilizes (adds) the antenna identifier of each antenna
system to carryout sending of a reply of an acknowledgment signal
(ACK/NACK signal). Here, "utilization" of the antenna identifier
signifies not that the antenna identifier is added explicitly to
send the ACK/NACK signal as a reply but that, for example, even if
it is determined that the number of such main antenna systems is
one, the sender apparatus issues an instruction of a frequency band
for the ACK/NACK signal of each antenna system to the receiver
apparatus and the receiver apparatus carries out sending of a reply
of the ACK/NACK utilizing the instructed frequency band. Therefore,
if the sender apparatus receives the ACK/NACK signal, then it can
analyze the frequency band of the signal to identify to which
antenna system the ACK/NACK corresponds. On the other hand,
"addition" of an antenna identifier signifies that an antenna
identifier is added explicitly to the ACK/NACK signal exactly as
illustrated in FIG. 5.
[0152] For example, taking notice of the process "0-2" in FIG. 5
sent from the antenna system Tx#1 (main antenna system is Tx#2) of
the sender apparatus 1 after transmission mode changeover occurs,
the receiver apparatus 2 produces a signal to which the antenna
identifier "0" which is (part of) a number element of the received
process "0-2" is added as an acknowledgment signal to the process
"0-2" by means of the ACK/NACK decision section 24 and sends the
produced signal as a reply to the sender apparatus 1.
[0153] Consequently, as a premise that synchronism with the
receiver apparatus 2 is achieved at least regarding a reply sending
timing of the acknowledgment signal to the sent process (in
particular, the sender apparatus 1 receives the acknowledgment
signal through timing adjustment with the receiver apparatus 2),
the sender apparatus 1 can recognize that the sent acknowledgment
signal corresponds to the process "0-2" by means of the re-sending
controlling section 16 and can correctly re-send the process "0-2"
from the main antenna system Tx#2 without re-sending in error of
the process "1-2".
[0154] It is to be noted that, where the sender apparatus 1 carries
out sending and reception of a process with the antenna identifier
omitted as described above (in particular, where all of processes
to be sent from the antenna systems other than the main antenna
system Tx#2 can be transmitted), even if a reply of the
acknowledgment is sent with the antenna identifier omitted, since
the timing adjustment is carried out, the sender apparatus 1 can
identify to which process the acknowledgment signal
corresponds.
[0155] An operation flow chart of the receiver apparatus 2 in the
present case 1 is depicted in FIG. 6.
[0156] In particular, the receiver apparatus 2 monitors and decides
whether or not a transmission mode changeover (change to the MIMO
diversity transmission) occurs (step S21), and if a transmission
mode changeover does not occur (in case of no at step S21), then
the ACK/NACK decision section 24 produces an acknowledgment signal
to which an antenna identifier which is a number element of the
received process is added and sends the produced signal as a reply
to the sender apparatus 1. Further, if the acknowledgment signal is
the NACK signal, then the HARQ reception processing section 22
retains the received process in preparation for the re-sending
synthesis (step S22).
[0157] On the other hand, if a transmission mode changeover occurs
(in case of yes at step S21), then the receiver apparatus 2 carries
out separation of the received process (identification of the
process number) by means of the process distribution section 26
(step S23) and decides whether or not an antenna identifier is
added (step S24). As a result, if an antenna identifier is added
(in case of yes at step S24), then the receiver apparatus 2
produces an acknowledgment signal to which the antenna identifier
which is a number element of the received process is added and
sends the produced signal as a reply to the sender apparatus 1
similarly as in the case at step S22, and, if the produced
acknowledgment signal is the NACK signal, then the HARQ reception
processing section 22 retains the received process in preparation
for the re-sending synthesis (step S25).
[0158] On the other hand, if an antenna identifier is not added (in
case of no at step S24), then since timing adjustment is carried
out, the receiver apparatus 2 sends a reply of the acknowledgment
to the sender apparatus 1 with the antenna identifier omitted, and,
if the acknowledgment signal is the NACK signal, then the HARQ
reception processing section 22 retains the received process in
preparation for the re-sending synthesis (step S26).
[0159] In this manner, in the present case 1, if a transmission
mode changeover (change to the MIMO diversity transmission) occurs
and each sending process needs to be identified among the antenna
systems Tx#i (Rx#i), then only the antenna identifier which is an
information element of the received process number is added to the
acknowledgment signal and the produced signal is sent as a reply to
the sender apparatus 1 while suppressing the information amount
thereof to a minimum, but, if all of the processes to be sent from
the antenna systems other than the main antenna system Tx#2 can be
transmitted and each transmission process does not need to be
identified between the antenna systems Tx#i (Rx#i), then addition
of the antenna identifier is omitted. Therefore, effective
utilization of wireless resources between the sender apparatus 1
and the receiver apparatus 2 can be achieved.
[0160] (Case 2) Where the ACK/NACK Signal is Sent as a Reply with a
Process Number Added Explicitly (FIGS. 7 and 8)
[0161] A diagram of a concept in the present case corresponding to
FIGS. 3 and 5 is depicted in FIG. 7. As seen in FIG. 7, even after
a transmission mode changeover (change to the MIMO diversity
transmission) occurs (refer to reference numeral 500), since timing
adjustment is not established between the sender apparatus and the
receiver apparatus, the receiver apparatus 2 sends the ACK/NACK as
a reply with a process number added explicitly.
[0162] For example, also in the present case 2, taking notice of
the process "0-2" sent from the antenna system Tx#1 (main antenna
system is Tx#2) of the sender apparatus 1 after a transmission mode
changeover occurs in FIG. 7, the receiver apparatus 2 produces a
signal to which the process number of the received process "0-2" is
added as an acknowledgment signal with regard to the process "0-2"
by means of the ACK/NACK decision section 24 and sends the produced
signal as a reply to the sender apparatus 1.
[0163] Consequently, the sender apparatus 1 can identify to which
process of which antenna system Tx#i the acknowledgment signal is a
reply (in the present example, to the process "0-2") by means of
the re-sending controlling section 16 irrespective of whether or
not the synchronism with the receiver apparatus 2 is established
regarding a reply sending timing of the acknowledgment signal to
the sending process, and the process "0-2" can be correctly re-sent
from the main antenna system Tx#2 without re-sending in error of
the process "1-2".
[0164] An operation flow chart of the receiver apparatus 2 in the
present case 2 is depicted in FIG. 8.
[0165] In particular, the receiver apparatus 2 monitors and decides
whether or not a transmission mode changeover (change to the MIMO
diversity transmission) occurs (step S31), and, if a transmission
mode changeover does not occur (in case of no at step S31), then
the ACK/NACK decision section 24 produces an acknowledgment signal
to which a received process number is added and sends the produced
signal as a reply to the sender apparatus 1. Further, where the
acknowledgment signal is the NACK signal, the HARQ reception
processing section 22 retains the received process in preparation
for the re-sending synthesis (step S32).
[0166] On the other hand, if a transmission mode changeover occurs
(in case of yes at step S31), then the receiver apparatus 2 carries
out separation of the received process (identification of the
process number) by means of the process distribution section 26
(step S33) and decides whether or not an antenna identifier is
added (step S34). As a result, if an antenna identifier is added
(in case of yes at step S34), then the receiver apparatus 2 adds
the received process number to an acknowledgment signal and sends
the acknowledgment signal as a reply to the sender apparatus 1
similarly as in the case at step S32, and, if the acknowledgment
signal is the NACK signal, then the HARQ reception processing
section 22 retains the received process in preparation for the
re-sending synthesis (step S35).
[0167] On the other hand, if an antenna identifier is not added (in
case of no at step S34), that is, if the sender apparatus 1 can
transmit all of the processes to be sent from the antenna systems
other than the main antenna system Tx#i and carries out sending and
reception of a process with the antenna identifier omitted, then
since addition of an antenna identifier can be omitted, the
receiver apparatus 2 sends the acknowledgment signal as a reply to
the sender apparatus 1 utilizing the number of the main antenna
system Tx#2 (process number similar to that of the conventional
method wherein the antenna identifier is omitted) without adding
the antenna identifier, and, if the acknowledgment signal is the
NACK signal, then the HARQ reception processing section 22 retains
the received process in preparation for the re-sending synthesis
(step S36).
[0168] In this manner, in the present case 2, if a transmission
mode changeover (change to the MIMO diversity transmission) occurs
and each sending process needs to be identified among the antenna
systems Tx#i (Rx#i), then since an acknowledgment signal is sent as
a reply to the sender apparatus 1 with a received process number
added, even if synchronism with the receiver apparatus 2 is not
established regarding a reply sending timing of the acknowledgment
signal to the sending process, the sender apparatus 1 can correctly
identify the process to be re-sent and re-sending in error of the
re-sent process can be suppressed with certainty.
[0169] Further, also in the present case 2, if all of the processes
to be sent from the antenna systems other than the main antenna
system Tx#2 can be transmitted and the sending antenna does not
need to be identified among the antenna systems Tx#i (Rx#i), then
since addition of the sending antenna is omitted, also effective
utilization of wireless resources between the sender apparatus 1
and the receiver apparatus 2 can be achieved.
[B] Description of Second Embodiment
[0170] FIG. 9 is a block diagram depicting a configuration of a
MIMO transmission system according to a second embodiment of the
present invention and corresponding to FIG. 2. The MIMO
transmission system (sender apparatus 1 and receiver apparatus 2)
depicted in FIG. 9 is different in comparison with the
configuration depicted in FIGS. 1 and 2 in that it includes a
process number addition section 17A and a process distribution
section 26A in place of the process number addition section 17 and
the process distribution section 26 described hereinabove. It is to
be noted that the configuration of the other part is same as or
similar to that described hereinabove with reference to FIGS. 1 and
2, and in FIG. 9, some of the components of the sender apparatus 1
(stream separation section 11, CRC calculation section 12 and
coding section 13) and some of the components of the receiver
apparatus 2 (CRC calculation section 22 and stream synthesis
section 25) are not depicted.
[0171] Here, the process number addition section 17A in the present
embodiment independently adds a process number to a HARQ block
(process) obtained by the HARQ sending processing section 14 such
that it is not competitive among all of the antenna systems Tx#i.
For example, addition methods described in (1) and (2) given below
are available.
[0172] (1) A method wherein, as seen in FIG. 9, process numbers are
successively added in an ascending order (or may be added in the
descending order) from the antenna system Tx#1 to the antenna
system Tx#n and, after a process number for a stream of the last
antenna system Tx#n is determined, the process numbers are
successively added in the ascending order again beginning with the
first antenna system Tx#1. In short, a method wherein a series of
process numbers are added repetitively to all of the antenna
systems Tx#i. For example, the process number regarding the antenna
system Tx#1 is, in a representation of a bit train, " . . . 00000";
the process number regarding the antenna system Tx#n is " . . .
00111"; the succeeding process number of the antenna system Tx#1 is
" . . . 01000"; and the succeeding process number of the antenna
system Tx#n is " . . . 01111".
[0173] (2) A method wherein, as seen in FIG. 10, a series of
process numbers which are independent of each other (are not
competitive with each other) for each antenna system Tx#i are
successively added in the ascending order (or may be added in the
descending order). For example, the process numbers for the antenna
system Tx#1 are " . . . 00000.about. . . . 00111"; the process
numbers for the antenna system. Tx#2 are " . . . 01000.about. . . .
01111"; and the process numbers for the antenna system Tx#3 are " .
. . 10000.about.11111".
[0174] In other words, the process number addition section
(controlling means) 17A in the present embodiment has also a
function as a group-based number production section which divides
information of a series of numbers into groups for each stream and
provides the number information in a corresponding group as the
process number (data block identification information) to be added
to the sending process for each of the streams to the HARQ sending
processing section 14 in order to implement addition control of a
process number which is not competitive among different streams,
which is similar to that in the first embodiment.
[0175] It is to be noted that, in both of the cases of (1) and (2)
given above, in order to avoid a subject similar to that of the
first embodiment, it is necessary to share an addition method of a
process number between the sender apparatus 1 and the receiver
apparatus 2.
[0176] In particular, for the process number identification,
process numbers and an addition method of the process numbers used
in the process number addition section 17A are stored in advance in
a memory or the like not depicted in the process distribution
section 26A of the receiver apparatus 2 and an addition method for
a process number is shared between the sender apparatus 1 and the
receiver apparatus 2 in advance. Consequently, the process
distribution section 26A can identify the process number of a
received process and control the signal separation and synthesis
process by the signal separation and synthesis section 21 so that
the received process is distributed and inputted to one of the HARQ
reception processing sections 22 based on the identified process
number.
[0177] In the following, operation of the MIMO transmission system
of the present embodiment configured in such a manner as described
above is described with additional reference to FIGS. 11 to 14.
[0178] First, in the sender apparatus 1, sending data are separated
into sending streams for the antenna systems Tx#i by the stream
separation section 11, and CRC codes are added to the sending
streams by the corresponding CRC addition sections 12, whereafter
the sending streams are coded into required error correction codes
such as turbo codes by the coding sections 13 and then inputted to
the HARQ sending processing sections 14.
[0179] In the HARQ sending processing sections 14, the sending
streams inputted from the coding sections 13 are subjected to a
HARQ process (converted into blocks), and process numbers provided
from the process number addition section 17A and non-competitive
among the antenna systems Tx#i as depicted in FIG. 9 or 10 are
added to the HARQ blocks (step S41 of FIG. 12). Then, the HARQ
blocks (processes) are stored in preparation for re-sending control
and are transferred to the sending section 15.
[0180] Consequently, the sending section 15 carries out the
wireless sending process described hereinabove for each of the
processes inputted from the HARQ sending processing sections 14 and
sends the resulting process from one of the antenna systems Tx#i to
the receiver apparatus 2. FIG. 11 illustrates a concept of a manner
in this instance. FIG. 11 is a view corresponding to FIG. 3 in the
first embodiment and illustrates the manner where the antenna
system for both of sending and reception are n=2 and besides the
addition method illustrated in FIG. 9 is applied. In FIG. 11, a
manner is illustrated wherein, to processes to be sent from the
antenna system Tx#1, even-numbered process numbers of "0", "2",
"4", . . . are successively added while, to processes to be sent
from the antenna system. Tx#2, odd-numbered process numbers of "1",
"3", "5", . . . are successively added independently of (so as not
to be competitive with) the process numbers regarding the antenna
system Tx#1 and the processes having the processes numbers added
thereto are sent to the receiver apparatus 2 (refer to solid line
arrow marks directed downwardly on the plane of FIG. 9).
[0181] It is to be noted that, also in the present embodiment, also
after the number of used antenna system decreases as in a case
wherein a transmission mode changeover occurs (refer to reference
numeral 500 in FIG. 11), the sender apparatus 1 maintains the
addition method of a process number by means of the process number
addition section 17A in a similar manner as described above to
carry out stream sending.
[0182] In the receiver apparatus 2, for example, in the case of
FIG. 11, the process "4" and the process "5" are received, and the
process numbers of them are identified and the processes can be
distributed to correct antenna systems Rx#i by the process
distribution section 26A. Accordingly, even if a transmission mode
changeover occurs, the HARQ reception processing section 22 can
carry out correct synthesis of the processes, that is, synthesis of
the processes of the same process number. In other words,
degradation of the matching property of synthesis can be prevented
(the subject 1 described hereinabove can be solved).
[0183] Further, also in the present embodiment, by contriving the
replying method of the ACK/NACK in such a manner as described in
cases 1 and 2 given below, also the subject 2 described
hereinabove, that is, the subject that re-sending in error of a
process occurs with the sender apparatus 1 and a process which
should originally be re-sent cannot be re-sent, can be solved.
[0184] (Case 1) Where ACT/NACK Signal is Received by Timing
Adjustment (FIG. 13)
[0185] Even after a transmission mode changeover (change to the
MIMO diversity transmission) occurs (refer to reference numeral 500
in FIG. 11), the receiver apparatus 2 carries out reply of an
acknowledgement signal (ACK/NACK) utilizing (adding) the antenna
identifier of each antenna system similarly as in the first
embodiment. Here, to "utilize" and "add" an antenna identifier
signifies similarly as in the first embodiment.
[0186] It is to be noted that, after the transmission mode changes
over to the MIMO diversity, in the first embodiment, if a process
number to which an antenna identifier is not added is received by
the receiver apparatus, then this signifies that a process is
thereafter sent only from the main antenna system. In the second
embodiment, since no antenna identifier is added to an access
number received, if a certain time period (T) elapses, then the
sender apparatus 1 thereafter sends a process only from the main
antenna system (in the case of FIG. 11, the antenna system Tx#2).
Therefore, after the time period T elapses, the receiver apparatus
2 can omit an antenna identifier in reply of an acknowledgement and
can send an acknowledge signal as a reply to the sender apparatus 1
using only the timing information of the main antenna system.
[0187] An operation flow chart of the receiver apparatus 2 in the
presence case 1 is depicted in FIG. 13.
[0188] As illustrated in FIG. 13, the receiver apparatus 2 monitors
and decides whether or not a transmission mode changeover (change
to the MIMO diversity transmission) occurs (step S51). If a
transmission mode changeover does not occur (in case of no at step
S51), then the ACK/NACK decision section 24 produces an acknowledge
signal which utilizes an antenna identifier (has an antenna
identifier added thereto) and sends the acknowledgement signal as a
reply to the sender apparatus 1. Further, if the acknowledgement
signal is the NACK signal, then the HARQ reception processing
section 22 retains the received process in preparation for
re-sending synthesis (step S52).
[0189] On the other hand, if a transmission mode changeover occurs
(in case of yes at step S51), the receiver apparatus 2 carries out
separation of a received process (identification of a process
number) by means of the process distribution section 26A (step
S53), and decides whether or not the time period T elapses (step
S54). As a result, if the time period T does not elapse (in case of
no at step S54), then the receiver apparatus 2 produces an
acknowledgement signal which utilizes the antenna identifier (has
the antenna identifier added thereto) and sends the acknowledgement
signal as a reply to the sender apparatus 1 similarly as at step
S52. Further, if the acknowledgement signal is the NACK signal,
then the HARQ reception processing section 22 retains the received
process in preparation for re-sending synthesis (step S55).
[0190] On the other hand, if the time period T elapses (in case of
yes at step S54), then the receiver apparatus 2 utilizes the timing
information of the main antenna system to send the acknowledgement
signal to the sender apparatus 1. Further, if the acknowledgement
signal is the NACK signal, then the HARQ reception processing
section 22 retains the received process in preparation for
re-sending synthesis (step S56).
[0191] In this manner, also in the present case 1, as far as a
transmission mode changeover (change to the MIMO diversity
transmission) occurs and it is necessary to identify each
transmission process among the antenna systems Tx#i (Rx#i), each
antenna identifier is utilized (added) to send an acknowledgement
signal as a reply to the sender apparatus 1. Then, if all of the
processes other than those by the main antenna system Tx#2 are
transmitted successfully and it becomes necessary to identify each
sending process among the antenna systems Tx#i (Rx#i), then only
the timing information of the main antenna system can be utilized
to send an acknowledgement as a reply, and therefore, effective
utilization of wireless resources between the sender apparatus 1
and the receiver apparatus 2 can be anticipated.
[0192] (Case 2) Where ACK/NACK Signal is Sent as Reply with Process
Number Added Explicitly (FIG. 14)
[0193] Even if a transmission mode changeover (change to the MIMO
diversity transmission) occurs (refer to reference numeral 500 in
FIG. 11), the receiver apparatus 2 sends the ACK/NACK as a reply
with a process number added explicitly. For example, if attention
is paid to the process "4" in FIG. 11 sent from the antenna system
Tx#1 (the main antenna system is Tx#2) of the sender apparatus 1
after occurrence of the transmission mode changeover, then the
receiver apparatus 2 produces, as an acknowledgement signal with
regard to the process "4", a signal to which the process number of
the received process "4" is added by means of the ACK/NACK decision
section 24 and sends the acknowledgement signal as a reply to the
sender apparatus 1.
[0194] Consequently, the sender apparatus 1 can identify a reply to
which process of which antenna system Tx#i (in the present example,
a reply to the process "4") the acknowledgement signal is by means
of the re-sending controlling section 16. Thus, the sender
apparatus 1 can re-send the process "4" correctly from the main
antenna system Tx#2 without re-sending the process "5" in
error.
[0195] It is to be noted that, also in the present case 2, although
the sender apparatus 1 can transmit a process only from the main
antenna system if a certain time period (T) elapses after
occurrence of a transmission mode changeover, after lapse of the T
time period, the sender apparatus 2 cannot send a process with a
process number omitted. In the present case 2, even if the certain
time period (T) elapses after occurrence of a transmission mode
changeover and the sender apparatus thereafter transmits a process
only from the main antenna system, since, different from the case
1, timing synchronism is not established, it is necessary to send
an acknowledgement with a process number added.
[0196] FIG. 14 illustrates an operation flow chart of the receiver
apparatus 2 in the present case 2.
[0197] In particular, the receiver apparatus 2 monitors and decides
whether or not a transmission mode changeover (change to the MIMO
diversity transmission) occurs (step S61), and if a transmission
mode changeover does not occur (in case of no at step S61), then
the ACK/NACK decision section 24 produces an acknowledgement signal
with a received process number added and transmits the produced
acknowledgement signal to the sender apparatus 1. Further, where
the acknowledgement signal is the NACK signal, the HARQ reception
processing section 22 retains the received process in preparation
for re-sending synthesis (step S62).
[0198] On the other hand, if a transmission mode changeover occurs
(in case of yes at step S61), then the process distribution section
26A carries out separation of a received process (identification of
the access number) (step S63) and produces and sends an
acknowledgement signal with the received process number added as a
reply to the sender apparatus 1 irrespective of whether or not the
T time period elapses. Further, if the acknowledgement signal is
the NACK signal, then the HARQ reception processing section 22
retains the received process in preparation for re-sending
synthesis (step S66).
[0199] In this manner, in the present case 2, as far as a
transmission mode changeover (change to the MIMO diversity
transmission) occurs and it is necessary to identify each
transmission process among the antenna systems Tx#i (Rx#i), an
acknowledgement signal to which the received process number is
added is sent as a reply to the sender apparatus 1. Therefore, even
if the sender apparatus 1 is not in a synchronized state with the
receiver apparatus 2 in regard to the sending timing of an
acknowledgement signal to a sending process, the sender apparatus 1
can correctly identify a process to be re-sent and can suppress
re-sending in error of a re-sending process with certainty.
[C] Description of Third Embodiment
[0200] The first and second embodiments described above demonstrate
that, by setting an addition method of a process number such that a
process number may not be competitive between antenna system, also
when the transmission mode changes over from the MIMO multiplex
transmission to non-MIMO multiplex transmission, correct synthesis
of processes can be achieved and transmission of streams can be
continued without interruption while preventing re-sending in error
of a process. However, the present embodiment demonstrates a
technique of continuing communication without interruption of
stream transmission also in conventional PARC or pre-coding wherein
a process number is added to a transmission stream independently
for each antenna system.
[0201] In the present embodiment, attention is paid to the fact
that, originally upon occurrence of a transmission mode changeover,
re-sending in error is caused by the fact that a process remains in
an antenna system other than the main antenna system. Therefore, in
order to prevent re-sending in error, when the transmission mode
changes over from the MIMO multiplex transmission, for example, to
the MIMO diversity transmission, the timing of the changeover
(reduction control of the stream number) is delayed in response to
the process (non-sent process) amount remaining in the antenna
systems other than the main antenna system (for example, the
changeover is carried out after transmission of all of the
remaining processes ends).
[0202] FIG. 15 illustrates a manner of communication between the
sender apparatus 1 and the receiver apparatus 2 where this method
is applied. In FIGS. 5, 7 and 11, if movement of the receiver
apparatus 2 from a MIMO multiplex transmission area 302 (refer to
FIG. 26) to another non-MIMO multiplex transmission area (MIMO
diversity area) 301 or 303 is detected, then the sender apparatus
immediately carries out changeover to the MIMO diversity
transmission (refer to reference numeral 500).
[0203] On the other hand, in FIG. 15, even if the movement (area
change) is detected at a timing indicated by reference numeral 600,
since the remaining process "2" exists for the antenna system. Tx#1
at this point of time, the sender apparatus 1 continues the MIMO
multiplex transmission, but the sender apparatus 1 actually changes
over the transmission mode from the MIMO multiplex transmission to
the MIMO diversity transmission only after the transmission of the
remaining process "2" ends (for example, at a timing indicated by
reference numeral 700). Consequently, even if such a special
process number addition method as in the first embodiment or the
second embodiment is not applied, communication can be continued by
simple and easy control without interruption of stream transmission
upon occurrence of a mode changeover.
[0204] It is to be noted, however, that, with the present method,
the transmission mode cannot be changed over to the MIMO diversity
until after re-sending of the remaining process "2" is completed
successfully. Therefore, for example, as illustrated in FIG. 16,
separately from the changeover threshold value for the MIMO
diversity transmission (threshold value A for the wireless
quality), a threshold value for changing over the transmission mode
to the MIMO diversity even if a remaining process exists (threshold
value B regarding the wireless quality<A) is provided. Then,
where the wireless quality of the receiver apparatus (mobile
station) 2 has a value between the threshold value A and the
threshold value B, if a remaining process exists, then the sender
apparatus 1 continues the MIMO multiplex transmission, but where
the wireless quality is lower than the threshold value B, the
sender apparatus changes over the transmission mode to the MIMO
diversity transmission.
[0205] It is to be noted that the function described above can be
incorporated, for example, as one function of the re-sending
controlling section 16 described hereinabove and also can be
incorporated as an individual controlling section (transmission
mode changeover timing controlling section). Further, it is
possible to allow the sender apparatus 1 to grasp the wireless
quality of the receiver apparatus 2 making use of a known method
such as, for example, a method of feeding back reception quality
information such as the SIR, CQI or the like measured by the
receiver apparatus (this similarly applies also in the following
description).
[D] Description of Fourth Embodiment
[0206] Here, a different method of continuing stream transmission
without interruption even in the conventional PARC wherein a
process number is applied to a sending stream independently for
each antenna system is described.
[0207] Also in the present embodiment 4, attention is paid to the
fact that, upon occurrence of a transmission mode changeover,
re-sending in error is caused by the fact that a process remains in
an antenna system other than the main antenna system similarly as
in the third embodiment. In particular, when, upon mode changeover
from the MIMO multiplex transmission to non-MIMO multiplex
transmission (MIMO diversity transmission), where, although the
wireless quality of the receiver apparatus 2 is higher than a
threshold value for changeover (threshold value A), it is lower
than another threshold value (threshold value C) (that is, the
threshold value C>threshold value A>threshold value B) and
besides sending data (process) does not exist in the antenna system
other than the main antenna system, the sender apparatus 1 does not
wait that the wireless quality becomes lower than the threshold
value Abut changes over the transmission mode to the MIMO diversity
transmission at a later point of time.
[0208] FIG. 17 illustrates an example of setting of the threshold
values A and C. Meanwhile, FIG. 18 illustrates a manner of
communication between the sender apparatus 1 and the receiver
apparatus 2 where the method of the present embodiment is
applied.
[0209] In FIG. 18, a manner is illustrated wherein, since the
sender apparatus 1 receives a NACK signal (refer to a broken line
arrow mark 610) with regard to the process "2" of the antenna
system Tx#1 after movement of the receiver apparatus 2 from a MIMO
multiplex transmission area to a non-MIMO multiplex transmission
area (MIMO diversity area) is detected (refer to reference numeral
600), re-sending of the process "2" occurs and, immediately after
an ACK signal (refer to a solid line arrow mark 620) to the
re-sending process, all remaining processes of the antenna system
Tx#1 are transmitted. If the wireless quality of the receiver
apparatus 2 has a value between the threshold value A and the
threshold value C after a point of time at which the remaining
processes disappear in this manner, then the transmission mode can
be changed over immediately to the MIMO diversity transmission at a
timing indicated by reference numeral 700.
[0210] It is to be noted that also the function described above can
be incorporated, for example, as one function of the re-sending
controlling section 16 described hereinabove and also can be
incorporated as an individual controlling section (transmission
mode changeover timing controlling section). Further, the threshold
value A, threshold value B and threshold value C described above
may be set simultaneously as far as the relationship of the
threshold value C>threshold value A>threshold value B is
satisfied.
INDUSTRIAL APPLICABILITY
[0211] As described in detail above, according to the present
invention, in a radio communication system, even where the number
of transmission streams between a sender apparatus and a receiver
apparatus varies (decreases), it is possible to maintain the
matching property of a data block of a re-sending synthesis target
to continue communication normally, and therefore, the radio
communication system is very useful in the field of the radio
communication technique.
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